End mill holders, adapters, and accessories connect rotary cutting tools (such as drills and end mills) to a milling machine. End mill holders and adapters hold tools more securely than a collet to prevent tools from spinning or pulling out during heavy cuts. End mill holder blanks mount to a machine spindle and have an unground end that can be machined to create a finished bore. End mill holder accessories secure end mills in the holder to ensure they stay in place during machining operations.